Calcium carbonate, iron ores and phosphate ores frequently contains a considerable amount of silicate. The presence of silicates is unacceptable in the beneficiation of these ores. It is therefore essential that the silicate content of the enriched mineral be reduced to a considerable extent, for instance, to a level below 1% by weight.
Silicate-containing minerals are generally removed from flotation systems by using reverse flotation technique whereby the silicates are floated in a pH range from natural pH to 10.5-11 and the beneficiated ore is concentrated in the bottom fraction. To accomplish this task, a cationic collecting agent is added to the mineral pulp in a conditioning tank so as to attach to the silicate bearing minerals surface thereby turning them hydrophobic. The silicates are then removed from the flotation cell through use of air bubbles injected into the mineral pulp.
Froth generation has become a key point in industrial flotation plants due to the many problems that an excess of froth can cause from difficulties to pump the material that contains the froth to environmental questions with governmental agencies. One common way to deal with excessive froth generation in full scale flotation plants is through the application of defoamers onto the froth. Defoamers are chemicals that are applied separately after flotation whenever froth volume or froth stability is an issue. Typically this is done as soon as it is collected in the flotation trough or as it travels to the concentration plant.
Various collecting agents are known in the art as silica collectors. For example, WO94/26419 discloses the use of quaternary ammonium compounds and an alkylene oxide adduct of an amine composition as silica flotation collector from calcium carbonate.
U.S. Pat. No. 4,995,965 discloses where silica is floated from calcium carbonate in the presence of collectors such as methyl bis (2hydroxypropyl) cocoalkyl ammonium methosulphate, dimethyl didecyl ammonium chloride, dimethyl di(2-ethylhexyl) ammonium chloride, dimethyl (2-ethyl-hexyl) cocoalkyl ammonium chloride, dicocoalkyl dimethyl ammonium chloride, and N-tallow alkyl 1,3-diamino propane diacetate.
U.S. Pat. No. 2,857,331 discloses beneficiation of, for example, calcite and phosphate by the use of a flotation reagent comprising a condensation reaction product of from 2.5 to 18 molecular equivalents of a commercially curde product selected from the group consisting of crude tall oil and tall oil pitch reacted with one molecular equivalent of a commercial polyalkylenepolyamine at a temperature of from about 300 to 4250° F.
WO2011147855A2 discloses the use of a polymeric quaternary ester product as a collector in a froth flotation process and to methods for the production of the polymeric quaternary ester.
U.S. Pat. No. 6,076,682 discloses the use of a combination of ether monoamine and ether polyamine as collector to remove silicate-containing minerals from iron ore by froth flotation in a pH range from 8 to 11 in the presence of a depressing agent for the iron mineral. The amine derivatives should present an aliphatic hydrocarbon group containing 6 to 22 carbon atoms wherein the ratio of ether monoamine and ether polyamine ranges from about 1:4-4:1.
U.S. Pat. No. 7,311,206 discloses the usage of collectors containing a quaternary ammonium compound to remove silicates from iron ore calling the attention to the high selectivity promoted by such chemicals in the removal of silicate-containing minerals by froth flotation in a pH range of 7-11.
WO 2012/139986A2 discloses the application of alkyl ether amine or alkyl ether diamines in the enrichment of iron ore by the removal of the silicate bearing minerals. The reverse flotation of iron ore is performed by using a collector or collector composition comprising at least one of the compounds: ROXNH2, ROXNH3+Y−, ROXNHZNH2 and ROXNHZNH3+Y−, where X is an aliphatic alkylene group containing 2 to 6 carbon atoms; Z is an aliphatic alkylene group containing 2 to 6 carbon atoms; Y is an anion; and R is an aliphatic group presenting a specific formula.
It is an objective of this invention to provide a new and improved method for the flotation of silicates from ores through use of a novel froth modifier and collector booster without compromising flotation performance.